Concussions and other head injuries are a major concern for athletes and others participating in activities where the head may be subjected to force. Concussions are a form of traumatic brain injury (TBI) and can range in severity from mild to life threatening. It is now known that concussions are more than temporary impairments of neurological function, which tend to resolve spontaneously, although, may have long lasting affects.
Repetitive concussions are extremely serious and can result in permanent structural changes to the brain, such as thinning of the corpus collosum, and are linked to chronic traumatic encephalopathy (CTE), a degenerative brain disease characterized by: memory loss, mood swings, cognitive impairment, depression, confusion, aggression and the decline of motor skills. Some studies have suggested that CTE may triple the risk of an early death.
The risk of concussions and other head trauma is especially prevalent in American football due to the number of impacts a player's head may receive. Despite every football player wearing a helmet, football has the highest incidence of concussions of the major sports. This fact illustrates that there is a need for a helmet that will further reduce the likelihood of a player receiving a concussion.
In order to understand how helmets may be improved, the different types of forces that can cause head trauma need to be understood. The two major types of forces are acceleration-deceleration (or linear impact) and rotational (or angular impact).
Briefly a linear impact occurs when a person's head is struck by a “straight-line” force causing the head to move in the direction opposite of the force. During such an impact the forces may cause the brain to move relative to the skull possibly even causing the brain to strike the inside of the skull. This movement and potential striking of the brain may cause stretching and tearing of neurons or brain cells.
An angular impact causes the head to experience rotational acceleration and is different from a linear impact. In this case, a force causes the head to rotate on its axis (corresponding to the neck) from side to side in a twisting motion. When a player's head is forced to rotate quickly over a large degree of rotation, nerve cells and blood vessels in the brain can be stretched and twisted. The twisting and tearing of an axon may result in the death of the neuron. Consequently the damage caused by rotational impacts may be particularly severe.
Helmets are designed to prevent head injuries, including concussions, by absorbing the impact forces to the head. The helmet should absorb and redirect that energy. Existing helmets do not effectively absorb linear impacts. They are also poor at absorbing rotational impacts. As a result of their potential severity, rotational impacts may be the cause of more sport concussions than linear impacts.
Current helmets are constructed with a hard outer shell using a chin strap to fix the helmet around the person's head, to protect against linear impacts. Current helmets typically use of an outer polycarbonate surface (hard) and an inner layer of heavy, snug fitting and shock absorbing padding (foam, air cells, etc.). Such helmet designs may be effective at absorbing the force of hard hits to the head and preventing both skull fractures and direct impact concussions by distributing the force across the entire surface area of the helmet. However, the shock absorbing padding is designed to fit closely to the player's head; if the helmet receives a rotational impact that rotates the helmet, the head is subject to the same rotational impact and also will rotate on its axis (neck) as a result of the shock absorbing padding.
Current football helmets in use today are not effective at providing protection against external forces that cause rotational impacts, which may lead to concussions. The inner padding fits so close to a player's head that rotational impacts to the helmet also cause rotation of the person's head. Adding to the danger is the general shape of helmets, especially helmets with facemasks, which may actually increase the amount of rotational force placed upon the player's head. This is a consequence of the force hitting the helmet a distance away from the head. The helmet may essentially act as a force multiplier (e.g. analogous to a gear or wheel) to increase the torque twisting the player's head.
In addition, the exterior of many sports helmets such as football helmets are designed in such a way that is likely to cause abrasions both to the player and to other participants. By way of example, and not limitation, helmets typically have a snap located on the exterior of the helmet for receiving a male-female snap attached to a chin strap and are typically accompanied by a bulky sizing mechanism. Other helmet designs have external hardware, brackets or screws used to affix helmet components such as a facemask to the helmet. These devices may create points of contact that may result in abrasions or lacerations to either the wearer or other participants.
What is needed is a light weight helmet that diverts and absorbs the energy caused by collisions to the head and reduces the potential for injury to the wearer and other participants.